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F21

F21 (10 flashes) — Outdoor coil temperature sensor

Haier · Air Conditioning

What does F21 mean?

This error means the sensor monitoring the temperature of the outdoor coil has failed or is providing incorrect readings.

Common Causes

  • Faulty defrost temperature sensor
  • Damaged Outdoor PCB

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Ensure the sensor is properly connected and not damaged.

  2. 2

    Restart the air conditioner.

  3. 3

    If the error persists, the sensor or Outdoor PCB may need replacement by a technician.

Browse all codes in this manual (103)
Verified technical data. Last updated: April 2026

Related Faults

1Error Code 1 — Outdoor PCB EEPROM fault10Error Code 10 — Defrost sensor fault11Error Code 11 — Compressor suction temperature sensor fault
Source: Haier Air Conditioning
Open Manual (Page 32)Search more codes in this manual